Southwark Council electoral register howler

I received a rather alarming letter from Southwark Council's Electoral Registration Officer today. Apparently despite requesting that my details were withheld from the public register the Council has sold them on to an unspecified number of organisations. This rather dreadful error, according to the letter, affects people who confirmed their existing details by phone or online and must be a clear breach of the Data Protection Act. No mention of compensation has been made (surprise) - only a rather vague mention of the fact that the organisations that received my information have deleted it. I don't trust this response at all and have demanded to know who received it, a written confirmation from each organisation that my information has been deleted and I've also asked the Council about their compensation proposals. This error must have affected a large number of people in the Borough.

The letter was a piece of spin - it conveniently omitted the breach of the Data Protection Act and the fact that the Council has in fact no control over whether whoever was sent the information actually retained it without telling them. It's really quite a serious breach of trust between the residents and the Council and suggests that they can't be relied upon to maintain the integrity of everyone's personal details. The email I sent them was quite direct and asked a lot of questions which I was perfectly entitled to - like where did the information go for instance. I've had no response so far.

This is what I have just sent to the electoral registration office of the Council.

Request for information under the Freedom of Information Act

Further to the letter received from Deborah Collins, Electoral Registration Officer of Southwark Council dated 27 February which arrived yesterday, please send me full and unabridged answers to the following questions.

Which organisations (including contact details, names and addresses) received the information about my details on the electoral register which the Council was not entitled to send out?

How much did each organisation pay for this information?

What guarantees and assurances has the Council received in writing from the recipients of my information that this information has been deleted, not used for marketing purposes and not passed on to other third parties?